Shock absorbing, wheelchair accessible, recreational surface area and method of constructing same

ABSTRACT

A recreational play area meeting a fall height requirement and being constructed essentially of one or more layers of shock absorbing synthetic material such as dimpled polystyrene, running to a perimeter structure consisting of nailer boards and collector drain. The shock absorbing layer is overlaid with polyethylene synthetic turf filled with a sand/rubber mixture for added shock attenuation.

FIELD OF THE INVENTION

This invention relates to recreational play areas and more particularlyto a recreational play area with shock-absorbing qualities forfall-caused injury protection constructed by laying one or more layersof shock-absorbing material over a base such as asphalt, concrete ordirt. The shock absorbing layer or layers are then overlaid withsynthetic turf to provide a natural appearance, as well as highdurability and low maintenance requirement. The surface is alsowheelchair accessible in that it provides a surface which is uniform andlow-friction.

BACKGROUND OF THE INVENTION

Recreational areas, such as playgrounds and/or playscapes, havetraditionally been characterized by dirt or turf surfaces which provideonly minimal protection against injury due to falls. More recently, ithas become popular to spread shredded rubber on the recreational surfacearea, around and under swings, slides, climbing bars and otherrecreational equipment. The principal purpose of such shredded lubber isto provide shock absorption to reduce the risk of injury associated withunintended falls.

These are significant disadvantages associated with the use of looselyspread particulate or shredded rubber. For one, the material is almosttotally lacking in aesthetic value. It is also difficult to travel inwheelchairs, scooters and similar devices for the handicapped due, inlarge part to its irregularity and high resistance to wheel travel. Inaddition, it provides relatively poor traction. Further, the shreddedrubber tends to get moved around; i.e., the area at the base of a slideor an area immediately under a swing is repeatedly contacted bychildren's feet and the shredded rubber is pushed away until there islittle or no shock absorbing material in a critical area. In otherareas, it gets piled up. The shredded rubber can be redistributed byraking but this requires regular maintenance, particularly after days oreven hours of heavy use.

In my co-pending application Ser. No. 11/732,298 filed Apr. 3, 2007 andassigned to The Shane Group, I describe a fall-safe play surface usingpoured-in-place technology, the depth of the poured material beingselected to meet a fall-safe requirement or standard. The poured layeris covered with synthetic turf.

SUMMARY OF THE INVENTION

In accordance with one aspect of my invention, a shock absorbing, fallsafe, uniform recreational play surface area is provided by laying oneor more pre-fabricated layers of sheet-like shock-absorbing materialover a base; i.e., the desired fall height safety function is met byselecting the number of layers of material rather than by pouring. Thisgreatly simplifies the installation procedure and eliminates the needfor mixing and pouring materials. The shock attenuating material layersare usually sold in rolls which are relatively easily transported andwhich may be joined to one another by taping seams. The area is definedby a base which may be natural or constructed of concrete or asphalt.Because of the uniformity of the surface, it is easily wheelchairaccessible and low in maintenance.

In accordance with a preferred embodiment of the invention, a collectordrain is created around at least part of the periphery of the play area.At least one ply or layer of thin impervious polymeric material is thenplaced over the base so as to extend to the collector drain, the areapreferably being sloped or grated toward the collector drain. Theimpervious layer is then overlaid with at least one layer of shockattenuating material which is then topped with a synthetic turf ofwear-resistant polyethylene or the like. The turf may be filled with amixture of sand and rubber to provide additional shock protection.

According to a second aspect of the invention, a method of constructinga recreation surface area over a base is provided. In accordance withthe method, the base area is leveled or graded slightly toward aperimeter for drainage purposes. At least part of the perimeter may bedefined by the construction of a collector drain filled, for example,with stone and containing a run of perforated drain pipe. The definedarea is then optionally overlaid with a thin sheet of impervious; i.e.,waterproof, polymeric material to promote drainage to the collectordrain. Thereafter one or more layers of shock attenuating material arelaid over the area and the seams, if any, are taped. Additional layersmay be used where higher equipment is to be installed. The totalthickness of material may be selected to meet a standard such as ASTM1292-04. Thereafter, a layer of synthetic turf is placed over theimpervious layer or layers. The turf may be partially filled with agranular mixture of sand and rubber.

BRIEF SUMMARY OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views and wherein:

FIG. 1 is a perspective view of a recreational play area which isconstructed in accordance of the invention and on which typicalplayground equipment is installed; and

FIG. 2 is a sectional view of an illustrative construction illustratinga collector drain.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT

Referring to FIG. 1, there is shown a recreational or playground surfacearea 10 having a perimeter 12 which is essentially rectangular withright angle intersections; only a portion of the perimeter 12 is shown.Outside of the perimeter 12, the recreational area 10 is surrounded bynatural turf 14; within the recreational area 10, the topmost surface isa partially filled synthetic turf 16 as hereinafter described in detail.The rectangular shape of area 10 is merely illustrative as virtually anyshape may be created.

As is typical, playground equipment including a slide 18 and aspring-mounted children's riding creature 20 are installed. The slide 18may have a height from about 3 to about 7 feet, the higher height slidesrecommending requiring a higher fall height safety factor than would beassociated with the lower mounted children's riding creature 20.

Referring to FIG. 2, a vertical sectional view along perimeter 12illustrates in detail the vertical structure of the recreational area 10and the manner in which it meets the adjacent area of natural turf 14.

The first step in the construction method is to define the area and toprepare a substantially level surface on a suitable base which may bedirt, asphalt, concrete or other stable material. The base surface ispreferably prepared in such as way as to be nearly flat but graded witha slope of between 0.5 and 1.0% toward the perimeter 12 for drainagepurposes from the interior area 10 toward the perimeter. A very largearea with only natural perimeter boundaries may be graded from thecenter outward. Other areas may be graded in only one or two directions,particularly is they are located on a sloped section of ground and/orabut a natural boundary such as a wall or sidewalk.

The next step is to define at least a partial perimeter. The first step,which is sometimes optional, is to build a collector drain 26 whichinvolves trenching below grade. More detail is provided below. Anaccompanying step is to lay into the base 22 a nailer strip 24 which, inthis case, comprises a line of pressure treated 2 inch by 6 inch nailerboards laid end-to-end along and immediately within the interior side ofthe perimeter 12. A flat, continuous surface must be prepared for theboards. The use of these nailer boards naturally suggests a play areashape defined by straight lines but which may have jogs or corners as isnecessary to accommodate other natural or manmade features in the playarea. In addition, the perimeter constructed in accordance with thisspecification may be only partial and may be integrated with othernatural perimeter features such as walls, buildings, waterways orsidewalks. Plastic nailer strips may also be used. In any event, theperimeter is flush with adjacent turf and presents no obstacle towheelchairs and the like.

The collector drain 26 is approximately 20 inches deep and is lined witha filter fabric of woven polypropylene filaments forming a stable anddurable network. This material is readily permeable to water,non-biodegradable and resistant to soil chemicals, acids and alkalis. Itis commercially available in rolls.

The drain trench 26 is filled with natural or crushed stone 32 andcontains perforated pipe 30 to convey water to a storm sewer or anadjacent waterway or a so-called French drain or simply a reservoir orditch. The collector drain is then filled with washed natural and/orcrushed stone with an average size of approximately ¾ inch.

The perimeter-defining nailer boards 24 are then placed along the sideof the collector drain around as much of the perimeter 12 of therecreational surface as is required. While wood boards are satisfactory,other materials such as plastic may be used.

The next step is to place over the base a continuous layer 34 ofimpervious, thin polymeric material, typically referred to as a“geomembrane” which is approximately 20 mils in thickness. This layer 34comes in rolls and is laid over the entirety of the surface area andspliced by tape as necessary. It runs over the nailer board 24 and issecured thereto by nails 46 which also runs through a restraint strip 48for purposes hereinafter described. The strip 48 may be plastic and hasan L-shaped cross-section. The geomembrane 34 is optional.

The next step is to overlay the impervious layer 34 with one or morelayers of shock absorbing, synthetic material layers 36, 38, 40, 42, thebottommost layer 36 extending partially over the collector drain 26 asshown and fully over the nailer board 24. A spike 44 or similar fasteneris used to secure the lowermost layer 36 to the nailer board 24. In thiscase, four layers of shock absorbing/attenuating material are showngiving a fall height safety factor of over 8 feet. Each layer isapproximately ¾ inch thick and, although it may be of varyingconstruction, is preferably itself a multilayer structure of which thecenter core is 42 mil polystyrene with conical dimples numberingapproximately 325 per square foot. The dimples are ⅜ inch in diameter atthe based and 5/16 inch in diameter at the top and the tops of thedimples are flat. The outer layers which sandwich the polystyrene sheetare nonwoven, polypropylene fabric glued to the tops of the dimples aswell as to the bottom surface of the center core. These materials, alongwith the impervious layer 34 also help to convey water horizontally fromthe play area up the field to and beyond the collector drain 24. Thelayers 38, 40, 42 edge immediately up to and are held in place by theedge restraint strip 48 as shown.

Next, the entirety of the topmost layer 42 is overlaid with syntheticturf 16 which is preferably partially filled with a sand/rubberparticulate material 49 to act as a ballast layer and also contribute tothe shock absorbing character of the overall structure. A preferredsynthetic turf is Radicci 69 oz. polyethylene and SF1 polypropylene witha pile height of about 1¾ inch and a weight of about 10 lbs. per linearfoot in a 15 foot width. Seams are taped during installation.

As shown in FIG. 2, a surrounding area of natural turf 14 is graded tobe essentially flush with the fill of the synthetic turf 16 at theperimeter 12 so as to create a natural integration or flow from thesynthetic turf 16 to the natural turf 14.

In accordance with the invention, the number of layers of shockabsorbing material may vary from one to four or more as required by thefall height requirements or standards or recommendations associated withthe equipment on the recreational surface 10. The base surface may, asdescribed above, be of any of a number of suitable materials orcombinations thereof. The grading may be accomplished by scraping anatural surface area down to a base layer or by simply flattening orpreparing a base layer and grading the surrounding area of natural turf14 up to it. The entire base may slope in one direction toward acollector drain or may be highest in the center and slope in alldirections toward a surrounding perimeter 12. All synthetic materialsused in the surface are completely recyclable. These and othervariations will be apparent to those skilled in the art.

1. A method of constructing a recreational surface area over a stablebase comprising the steps of: defining a perimeter of the area;overlaying the area with one or more layers of shock absorbing syntheticsheet material to a thickness providing a fall height safety factor forthe area; and overlaying the shock absorbing material with syntheticturf.
 2. The method defined in claim 1 wherein the step of defining theperimeter includes the installation over the base of a nailer strip andoverlaying the area with a thin impervious membrane.
 3. The methoddefined in claim 2 including the further step of securing the imperviousmembrane to the nailer board strip.
 4. The method of claim 1 furtherincluding the step of building a collector drain in the base along atleast part of the perimeter.
 5. The method defined in claim 4 whereinthe step of building a collector drain includes forming a trench,placing a perforated drain pipe in the trench and substantially fillingthe trench with stone.
 6. The method of claim 2 including the furtherstep of securing an edge restraint to the nailer strip immediatelyadjacent the outer edges of the shock absorbing material.
 7. The methodof claim 4 wherein the shock absorbing material comprises multiplelayers and the bottommost of said multiple shock absorbing layerspartially overlies the collector drain.
 8. The method bf claim 1 whereinthe base is graded toward the perimeter.
 9. The method of claim 1including the further step of filling the artificial turn With agranular mixture made up of sand and rubber.
 10. The method of claim 1further including the step of grading the area around and outside of theperimeter with top soil and natural turf to be essentially flush withthe synthetic turf overlying the area.
 11. A shock absorbingrecreational surface constructed over a stable, substantially flat baselayer comprising: a base; at least one layer of shock absorbingsynthetic prefabricated sheet material overlying the base; and a layerof synthetic turf overlying the layer of shock absorbing synthetic sheetmaterial.
 12. A recreational surface area as defined in claim 11 whereinat least part of the area perimeter is defined by a collector drain. 13.A recreational surface as defined in claim 11 further including a nailerstrip installed on the base restrainingly adjacent said layer of shockabsorbing material, and an impervious sheet underlying the shockabsorbing layer and secured to said nailer strip.
 14. A recreationalarea as defined in claim 11 wherein the synthetic turf is filled.
 15. Aresilient recreational area having a perimeter and comprising: asurface; a layer of structurally bound resilient material placed overthe foundation surface and having a thickness adequate to provide apredetermined degree of injury protection; a layer of synthetic turfplaced over the resilient material layer; and a drain structure locatedadjacent at least a portion of the perimeter.
 16. A resilientrecreational area as defined in claim 15 further including an imperviousdrain blanket placed over the foundation but under the resilientmaterial layer and partially overlying the drain structure.